The major objectives of this research are to clarify the mechanisms by which zinc is incorporated into mammalian sperm keratins and obtain further information about the function of this and other trace metals in mammalian spermatozoa. Radioactive zinc, cystine and histidine will be administered to male rats to examine the schedule of incorporation, intracellular location and protein components involved in the uptake of Zn by the testis and its incorporation into the sperm. Polyacrylamide gel electrophoresis will be used to resolve the Zn-binding proteins analytically and, in some cases, to obtain purified proteins. The effects of androgen and gonadotrophins on Zn uptake will be investigated. The distribution of Zn in human sperm will be examined and the zinc-binding proteins resolved electrophoretically. The effects of marginal Zn or Cu deficiency on sperm keratins will be evaluated by comparing the stability and ultrastructural appearance of the keratinoid structures in normal and deficient rats. Tracer studies and atomic absorption spectrophotometry will be undertaken to establish the intracellular location of other trace elements in the sperm, such as Cu, Mn and Se, as well as that of Zn.